The present invention is directed to surgical instruments and, more particularly, to a trocar assembly which may also be useful for endoscopic procedures.
Conventional trocar assemblies utilize trocar obturators or mandrels having pointed tips used to puncture the walls of a body cavity for either draining fluid or for endoscopic procedures. However, the conventional trocar obturator or mandrel is made of stainless steel and utilizes a piercing and cutting end or head tip made from various parts including cutting blades. The obturator or mandrel itself may be relatively complicated, being formed of individual parts joined together by fabrication for the final instrument.
The piercing and cutting surfaces for the conventional trocar mandrel is generally pyramidal in form, and is usually provided with flat side bevels, the surfaces of which converge to define cutting edges. The difficulties and disadvantages of these conventional forms of trocar obturators or mandrels are many. Since these devices are re-used for many surgical procedures, in time, the cutting edges become dulled and nicked from the repeated uses, and perhaps by an occasional inadvertent dropping of an instrument on the floor. Continual use of such devices also increases the risk of initiating and perpetrating the spread of infection to patients who have the misfortune of being subjected to these re-used instruments. In addition, it has also been found that stainless steel has a very high coefficient of friction and has the tendency of dragging or pulling the adjacent walls of a cavity as the instrument is being inserted or removed, thereby causing trauma, undue ripping and/or tearing of tissue around the affected area.
A trocar is disclosed is U.S. Pat. No. 4,654,030 which employs an elongated obturator having a pyramidal shaped piercing head comprising three flatly formed surfaces resulting in a blunt piercing end. These formations of faces will unduly damage the tissue walls surrounding the opening in which the instrument is inserted, by producing ripping and tearing of tissue.
Another conventional embodiment of a trocar obturator is disclosed in U.S. Pat. No. 4,601,710. One of the embodiments is directed to a tubular body having a frustal conical end slotted to receive blades, while in a second embodiment, the piercing tip is formed with three bevels at the end of a cylindrical body portion. By the nature of the disclosed side faces or blades which are blunt and lack suitable curvature for cutting tissue, considerable force is necessary to produce penetration with ensuing damage to the surrounding walls of the tissue. At times, such force may be beyond the capability of the user, and certainly, the application of large amounts of force will be beyond the skill of the operator to apply with precision and efficiency.
Another type of trocar, that for animal use, is disclosed in U.S. Pat. No. 3,039,468. The trocar instrument in this patent utilizes grooves formed in the shank of the trocar device beyond a conical piercing tip. In this arrangement, the conical tip proceeding the grooved sides is too long and would constitute a delay in the use of the grooved portion for penetrating tissues and walls of a cavity. In any event, circular elongated grooves do not lend themselves as efficient types of curves for instruments of this sort which are inserted through tissue and cavity walls for a relatively long distance. Such curves, in fact, add more surface to the instrument thereby increasing the force necessary for the manual insertion and removal of the instrument.
A hyperdermic needle is disclosed in U.S. Pat. No. 3,090,384 which provides a very sharp piercing tip in combination with cutting edges formed of the same material used for the needle. The side surfaces for the cutting faces are flat and may be useful for hyperdermic needles since these instruments have a very small diameter ratio relative to the length of the penetrating piercing tip. Such an arrangement, however, would not be useful for a trocar obturator since the two faces are flat and are not efficient for preventing the dragging and tearing of tissue as the same is inserted into tissue or walls of a cavity.
The principal object of the present invention is to utilize a trocar obturator or mandrel made from inexpensive material and comprising a simple article of manufacture which may be thrown away after a single use.
Another object of the present invention is to utilize a trocar obturator made from material which has a coefficient of friction well below that of stainless steel utilized in conventional obturators and thereby avoid unnecessary damage to tissue during use.
Still another object of the present invention is to minimize the prospect of the initiation and spread of disease or infection made possible with conventional trocar obturators having an assemblage of individual parts which provide spaces wherein contaminants and dirt may become imbedded, and which may not even become fully cleaned, when these instruments are sterilized.
Still another object of the present invention is to utilize a novel design of cutting faces at the piercing end for a trocar obturator which design results in the efficient cutting of tissue around the point of insertion.
In order to avoid the problems and disadvantages of the conventional trocar obturator or mandrels as described above, the present invention was devised so that the obturator or mandrel comprises a single article of manufacture and not the assemblage of individual parts brought together as the finished instrument. The invention also provides that the trocar obturator or mandrel be made of thermoplastic polymeric material which has a coefficient of friction much less than that of stainless steel, or other metals, or metallic plating used in the market today. Furthermore, the invention envisions the use of a more novel arrangement of compound surface formations at the piercing and cutting end of the obturator, the sides being arranged to form cutting edges which, upon movement through the walls of the cavity being worked upon, will ensure that the pierced edges of tissue will slide relatively unimpeded during the cutting stage of the insertion of the obturator so that the tissue does not tear or rip open during this step.
The above recited objects and other advantages will become apparent from the following description taken in conjunction with the drawings wherein: